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CYA added but there is no stabilizer in the pool

I've got a question regarding some CYA reading in my brother-in-laws pool. He's been having problems in his 21" round above ground pool with algae. He has a DE filter and uses pucks in a floater.

I did a complete set of tests using my <1 year old ps234 test kit. Within those results the main problem was his CYA, it had no reading of CYA. He stated that he added an unknown quantity of CYA in spring. In previous springs I have checked his water and his CYA always seems to go to zero (year after year).

I then told him to read the CYA instructions and add enough to raise the level to 30. He added some of the CYA that he had used earlier in the spring to his skimmer. After two days I measured the CYA and chlorine again...it was still clear as can be with the CYA test tube filled.

I have tested two other pools for CYA readings and both tests went fine and gave good readings. I'm at a loss.

Could it be possible that the container CYA goes bad? or could you buy some bad CYA?

I told him to pick up some new stabilizer and we would see where he is at in two days???????

Yes, it takes several days, up to a week, for CYA to disolve. Plus it is difficult to measure levels below 20, they can often appear to be zero. Wait the full week from the time the CYA was added and test again.

Another possibility, if he added it to the skimmer it goes into the filter and slowly disolves. If you backwash/clean the filter before the week is up you are washing the CYA down the drain.

Easy way to tell if the chemical in his CYA container is, indeed, CYA. Drop one granule of it into your CYA dispensing bottle, fill with pool water to the pool water line, fill with reagent to the reagent line, shake for a minute or two. It should turn VERY cloudy!

Easy way to tell if the chemical in his CYA container is, indeed, CYA. Drop one granule of it into your CYA dispensing bottle, fill with pool water to the pool water line, fill with reagent to the reagent line, shake for a minute or two. It should turn VERY cloudy!

Ahhha! nice one

He said he used all the CYA...but I'll check to see if there is one granule left. I bet there is

I know you said your pool looks clear and all, but I had a huge problem with CYA vanishing out of my pool. Turns out something was eating it. I had a pretty good chlorine demand, but did not realize it because I did not understand pool chemistry and how the SWG worked. Just for the fun of it, maybe raise your FC to 5 in the evening, and see if it is still 5 in the morning. If it is not 4.5 or more in the morning, there might be something in your pool eating up the CYA.

If there is, you can super-shock your pool for a few days to 20 FC and hold that level until it is stable overnight. Then your CYA might hold. Just a thought.

I know you said your pool looks clear and all, but I had a huge problem with CYA vanishing out of my pool. Turns out something was eating it. I had a pretty good chlorine demand, but did not realize it because I did not understand pool chemistry and how the SWG worked. Just for the fun of it, maybe raise your FC to 5 in the evening, and see if it is still 5 in the morning. If it is not 4.5 or more in the morning, there might be something in your pool eating up the CYA.

If there is, you can super-shock your pool for a few days to 20 FC and hold that level until it is stable overnight. Then your CYA might hold. Just a thought.

Itabb, the chlorine demand you had in your pool was from an overdose of ascorbic acid you put in to remove stains. Chlorine gets 'eaten' by a chlorine demand in the water NOT CYA. You just did not have enough CYA in your pool for your SWG and were afraid to raise it. I know this because I was the main one helping your along with Chemgeek over on poolspaforum just 2 weeks ago with this problem. There is some specualtion that CYA can be consumed by denitrifying bacteria in a pool closed for the winter but this is a very slow process and requires anerobic conditions and no water circulation. It will not happen overnight.

My little ascorbic acid problem resulted in an algae bloom. I was told, though not by you or Richard, that algae eats CYA. It is the only thing that makes sense as to why I have put 20 lbs of CYA in my system in the last 3 months and only have a level of 70-80 to show for it. What I was seeing was a very fast eating of my CYA. I was losing half of my CYA in a week, if not faster.

Of course, this is speculation because I was not good at measuring back then and the pool store was helping (in a bad way). I guess I could turn my pool to **** and measure how fast CYA gets eaten, if at all. Then again, I'd be dealing with a family revolt, so I'll hold off on that one.

While my pool is clear...but my brother-in-laws pool is the one in question. He does have an algae problem that he's been fighting all year, which is due to having no measurable amount of CYA in his pool. He recently bought a new container and added that...we'll wait and see what it goes up to.

itabb...thanks for your thoughts. But if you could grow a fast eating CYA algae in your pool...I would suggest that you bottle it and sell the stuff. I would guess the inconstancy with numbers was due to measuring errors rather than quick CYA fluctuations...but who knows

Nevertheless, 20 lbs of CYA should result in a CYA reading of 160. I don't backwash, so I only deal with splashout. I would have had to splash out 7500 gallons of water in 3 months, and my water bill does not show that (pool is on a separate line). So, no matter how improbable, something ate the CYA. And pretty fast too. I'm actually due to measure the CYA today. It was 50 last time I checked and I added 60 oz (saved the other 4oz for the spa). I expect to see 80, though I won't be surprised to see 70. It may also be that Leslie's CYA is junk, in which case, I'll switch to dichlor as my CYA supply, since people don't seem to have a problem reaching levels of CYA 150 using dichlor. That and I can get dichlor at Home Depot for a lot less than Dichlor at Leslies, and 8 lbs of dichlor is a bit cheaper than 4 lbs of CYA. Guess we'll see.

I have heard of at least one other recent case where someone suspected that a pail of CYA didn't actually contain any CYA. A second pail from the same place was fine. That can't be very common or there would be more reports, but you can't rule it out.

Algae doesn't break down CYA. However some bacteria do break down CYA. It is not uncommon to have various kinds of bacteria in the water when you have algae. Generally the kind that break down CYA don't show up during the summer. They seem to prefer winter time. However, no one has really studied what the preferences of the kind of bacteria that break down CYA are.

Well, the algae bloom I had was from the ascorbic acid OD demand on FC. However, I would not be surprised if I did not also have a bacteria problem from over the winter which was never solved until I held the FC over 20ppm to deal with the ascorbic acid and algae. Maybe I still have that bacteria problem . . . I'll find out tonight, I suppose.

Cyanuric Acid is an acid, but adding a base simply shifts from having cyanuric acid to having cyanurate ion and this still protects chlorine from breakdown from sunlight. Adding a base will not destroy the core ring in CYA. It is known that certain soil bacteria will degrade CYA slowly via enzymes and we believe these sometimes make their way into pools when chlorine levels are low. So if you let your pool go over the winter, then such bacteria may thrive (and algae may as well) and the bacteria will break down the CYA. However, when they do so, they produce ammonia (and carbon dioxide) and this takes a LOT of chlorine to break down. So the chlorine demand upon opening after winter will be HUGE if the CYA was converted to ammonia. Testing for the ammonia is easy since adding chlorine will result in a very high combined chlorine (CC) measurement almost immediately.

Cyanuric Acid can also be broken down (oxidized) by very high levels of chlorine with sodium hypochlorite at 2.6 times by weight the amount of CYA (ideal is stoichiometric molar 6:1 to 8:1 chlorine to CYA) and at a pH of 9-10. For every 1 ppm CYA, it would take 3.3 to 4.4 ppm FC and the high pH to break down. Since even the high yellow/mustard algae shock FC recommendation is 60% of the CYA level and the pH is well below 9, we don't see degradation of CYA from shock levels of chlorine.

I find it interesting that my TA continues to rise. it was 90 before adding borates, it was 110 when I hit 30ppm borates. Now it is 120.

Anyway, my last CYA measurement a week ago or so was 50. Today's measurement is 60. And that is after adding 60oz of CYA. My goal is 80ppm CYA. So what happened to 20ppm CYA? My 50 CYA measurements was June 9th . I added the CYA on Jun 20th or 21st.

You know what I think? Conspiracy! I think the Leslie's CYA isn't really much CYA at all. I'm going to switch to Dichlor to get my CYA. I'm going to have to shock the pool anyway after this insane weekend. It just seems to me that people who use dichlor and trichlor on a regular basis have no problem at all getting their CYA levels up to extreme levels. Surely, I can use it to get mine up just 20ppm. That'll be cheaper than $20 for 10ppm CYA.

Let's see, I added 20lbs of CYA, I get 60ppm. That's 3ppm per lbs, that's 12ppm per 4lb pack, that's $100 in CYA. I've been suckered.